Is more of the same a bad thing? More chocolate? More shoes? More long days lounging by the pool?

Considering the original LocoRoco stands as one of the best games on PSP – arguably one of the best on any console, in fact – we're not questioning the arrival of LocoRoco 2. Certainly, the series is among gaming's most distinctive in terms of a style that has uniqueness stamped all over its Teletubby-bright visuals and diverse nursery rhythm-style chanting tunes.

So there should be no disagreement over the fact that LocoRoco 2 offers more of the same. In fact, the starring characters – the charming LocoRoco themselves – remain exactly the same as before.

You grow your space hopper-esque character from small blob to a bigger, blobbier one by eating red berries and, at strategic points, can choose to break him down into numerous little LocoRoco. The various coloured Loco, which are unlocked as you play, have their own unique characters, and they all sing different tunes as you roll, jump, fall, fly and are sucked, dragged and fired through a rainbow mixture of levels – everything from a penguin's guts to puffer fish-infested seas.

The levels are instantly familiar if you played the original game. And if you did, you have the immediate advantage of knowing that the big snouted Chuppa is going to suck you up and spit you into the air, that secrets lie through evaporating walls everywhere, and that little waving MuiMui men are sleeping in hidden rooms throughout every level waiting to greet you with a new piece of furniture for your MuiMui house. (If you didn't, don't worry, this will all make sense after spending a little time in LocoRoco land.)

What you won't know though is this: the black Moja muck that's splattered about can now be cleaned up to earn musical notes; that boss battles await you; and those musical interludes where your LocoRoco sing to an assortment of happy, sad and sometimes just plain confused looking characters are now interactive thanks to the introduction of notes that need hitting in rhythm.

Equally, you won't be expecting the afro-wearing dude's afro to suddenly fall off, or your LocoRoco to wear it and then roll delightedly down a series of slopes using the afro like a battering ram against boulders. Or that your Loco will suddenly dive under the water and swim, rather than bounce, among a series of weird and wonderful sea creatures, or attach itself to a firework that – once the fuse has burnt down – is fired skywards. You might not have thought you'd find unlockable mini-games (including takes on pinball, horse racing and Whack-a-Mole) and stickers, which you can spend happy time arranging in position in a sticker book.

Essentially, there's a lot in LocoRoco 2 that's familiar – and we wouldn't want it any other way. As already argued, this doesn't mean the game is any less delightful to play than it was first time around because there's no less to discover. LocoRoco 2 will enthral, enchant and charm the pants off anyone who sits down with it, and that includes both the casual and hardcore crowd, since the game masters the tricky art of providing something for everyone.

What has thankfully remained the same is the simple control system. The LocoRoco are moved solely using the PSP triggers – L tilts the world left and R tilts it right to make them roll in that direction, while pressing both together makes them jump. Hitting Circle either separates the LocoRoco or binds them back together, and it's also used in the rhythm sections.

So the game's simplicity hasn't been messed with at all. Instead what's been concentrated on is expanding its content. There are more unlockables (if you hit certain criteria within a level you even trigger quests and level-up) and the whole game is much longer than it was previously. Certain ideas from the original title have been stretched out, too – for instance, the level where you're inside the springy pink insides of the aforementioned penguin are similar to a level in the first LocoRoco, but now violating certain parts of the penguin make him stand up or lie down, with gravity and the areas you can reach changing accordingly.

In that context, it's also worth pointing out that alongside all its other attributes, LocoRoco 2 is a very funny game. The high-pitched childish voices of the LocoRoco should be annoying, as should the unashamed cuteness of it all, but the enthusiasm of the characters in this world is infectious. Their boldly displayed emotions ranging from delight (when they're happily singing) to trepidation, curiosity and even outright fear when they're standing too close to an evil Moja. And the world they inhabit is a place of discovery, as explorable and damn loveable as any Mario game. It doesn't have taxing puzzles or particularly tricky platform sections or very responsive controls at times but everything in the game works and suits it perfectly.

Criticisms? Well, on occasion, losing one of your Locos feels a little unfair, and there's no way of getting them back so if you want the perfect end-of-level result you'll need to start again. The boss fights aren't the most epic, either – as you'd imagine since your only real form of attack is jumping. And it'd be nice to know what level criteria you're trying to fulfil to get the level reward.

But the negatives are minute. If there's one PSP game you should be playing this Christmas it's LocoRoco 2. Any video game whose charm can intoxicate you more comprehensively than countless shots of Baileys should be considered both compulsive and essential.